The present invention relates to an apparatus for controlling a driving motor. More particularly, to an apparatus which controls and automatically stops the driving motor of a vehicle while the vehicle stops.
Various types of vehicles with an automatic transmission are known. One known automatic transmission transmits driving force from the driving motor, such as an engine, to driving wheels when the transmission is set in a driving range, such as a D range, and the vehicle moves at a certain or lower vehicle speed when the accelerator pedal is released. Recently, for the purpose of improving fuel consumption, a vehicle has been developed with a driving force decreasing unit, which decreases the creep driving force when the brake pedal is depressed while the vehicle is in an idling condition and moves at a certain or lower vehicle speed, and a vehicle with a driving motor stopping unit, which automatically stops the driving motor while the vehicle stops in an idling condition.
In creep running, the vehicle with an automatic transmission moves slowly as if it creeps along the ground when the transmission is set to a running range, such as a D or R range and the accelerator pedal is released (the driving motor is in an idling condition).
The decision to have the driving motor stopping unit stop the driving motor is based on a determination of whether or not the detected vehicle speed becomes 0 km/h. The accuracy of the detected vehicle speed is determined by a vehicle speed sensor and an ECU (Electronic Control Unit) calculating vehicle speed based on information obtained from the vehicle speed sensor. For this reason, depending on the detectability of the vehicle speed sensor or throughput of the ECU, the vehicle speed may be regarded as 0 km/h even if the vehicle is not completely stopped. For example, if the vehicle speed sensor cannot detect a minimum vehicle speed of less than 1 km/h, the detected vehicle speed is 0 km/h, notwithstanding that the vehicle is actually moving at a vehicle speed of less than 1 km/h. When the detected vehicle speed becomes 0 km/h, the driving motor stopping unit automatically stops the driving motor, even if the vehicle is not completely stopped. If the creep driving force is greater before automatically stopping the driving motor, a braking force greater than the creep driving force is required in order to stop the vehicle, and a large amount of driving force difference exists until the driving force falls to zero. Therefore, if the driving motor is automatically stopped before the vehicle stops fully and the driving force falls to zero, the vehicle often stops suddenly due to a greater braking force and greater driving force difference.
In view of the above, the present invention seeks to provide a an apparatus for controlling a driving motor which eliminates sudden stops by the vehicle, even if the driving motor is stopped before the vehicle stops completely.
According to the present invention, there is provided an apparatus for controlling and stopping a driving motor for a vehicle, which vehicle allows transmission of driving force from a driving motor to driving wheels, irrespective of releasing an accelerator pedal at a certain or lower vehicle speed when a transmission is set to a driving range. The apparatus also includes a driving force decreasing unit which switches the driving force based on depression of a brake pedal such that the driving force is made lower when the brake pedal is depressed than when the brake pedal is released, and the apparatus includes means for stopping the driving motor after the driving force is decreased by the driving force decreasing unit.
There is also provided a vehicle with an apparatus for controlling and stopping a driving motor, which vehicle allows transmission of driving force from a driving motor to driving wheels, irrespective of releasing an accelerator pedal at a certain or lower vehicle speed when a transmission is set to a driving range. The apparatus also includes a driving force decreasing unit which switches the driving force based on a brake pedal being depressed such that the driving force is made lower when the brake pedal is depressed than when the brake pedal is released, and the vehicle is controlled such that the driving motor is stopped after the driving force is decreased by the driving force decreasing unit.
According to such an apparatus for controlling and stopping a driving motor and vehicle, because the driving force is decreased before stopping the driving motor, the depression force of the brake pedal is reduced (i.e., braking force becomes smaller) before stopping the driving motor, and the driving force difference becomes smaller, even if the driving motor is stopped so that the driving force falls to zero. As a result, the vehicle does not stop suddenly if the driving motor is stopped before the vehicle stops completely.
The term xe2x80x9ca certain vehicle speedxe2x80x9d indicates a vehicle speed just before the vehicle stops. Therefore, if a certain vehicle speed is 5 km/h, as an example in the preferred embodiment, the vehicle speed range xe2x80x9cat a certain or lower vehicle speedxe2x80x9d includes vehicle speeds from 0 km/h (when the vehicle stops) to 5 km/h.
Further, because the purpose of the invention is to prevent sudden stops of the vehicle due to the stopping of the driving motor (driving force is zero) before the vehicle stops completely, the wording xe2x80x9cafter the driving force is decreased by the driving force decreasing unitxe2x80x9d does not include a condition where the driving force is zero.